In vitro testing for the diagnosis of polysensitization to vespids: CAP inhibition

Background. In Southern Europe countries sensitization to both Vespula spp. and Polistes spp. can be observed in 50.5 to 61.5% of anaphylactic sting reactions, hindering the distinction between vespid cross-reactivity and genuine sensitization. CAP-inhibition is regarded as the reference method in such cases. Methods. Retrospective study, including candidates to VIT with double sensitization (skin testing, specific IgE to whole venom extracts and to molecular components) to at least two different vespid venoms (Vespula spp., Polistes spp. and/or Vespa velutina). CAP-inhibition was done in all patients. Results.  A total of 26 patients were identified (16 double sensitizations to both Vespula spp. and Polistes spp., and 10 sensitizations to all three venoms). After CAP-inhibition, VIT decision was changed in 57.7% (15/26) of cases and maintained in the remaining 11 patients (42.3%). Overall, triple VIT was changed to single VIT in 1 patient, from double VIT to single VIT in 9 cases, and from single VIT to double VIT in 3 patients. In single VIT, venom type was changed in the remaining 2 patients after CAP-inhibition. Conclusions. Our findings support the usefulness of CAP-inhibition in clarifying multiple positivity to vespid venoms when conventional diagnosis fails to distinguish cross-reactivity from genuine sensitization. CAP-inhibition may help to prevent costs of prolonged or unnecessary double-VIT treatment, as well as the risks of undertreatment.